1. Field of the Invention
The present invention is directed to an x-ray intensifier having an electrode system for focusing the electrons generated on a input luminescent screen by the incidence of x-rays thereon, onto an output luminescent screen.
2. Description of the Prior Art
X-ray image intensifiers are used in x-ray diagnostics for converting an x-ray shadow image, produced by irradiating a patient with x-rays, into a visible image. A video camera tube is connected to the output of the x-ray image intensifier, the output signals of this tube being supplied to a monitor via a video chain. The examination region is displayed as a picture on the monitor.
A known x-ray image intensifier is described in the book "Das Roentgenfernsehen," Bauer et al., 1974, pp. 54-56. This known x-ray image intensifier has a vacuum vessel with an input luminescent screen with a photocathode disposed at one end face and an output luminescent screen disposed at the other end face. An electrode system is disposed between the screens for accelerating and focusing electrons generated by the incidence of x-rays on the input luminescent screen onto the output luminescent screen. The electrode system is formed by a plurality of cylindrical or annular electrodes having respectively different diameters, to which different voltages are applied for focusing the electrons generated at a point of the input luminescent screen onto a corresponding point of the output luminescent screen. These electrodes are in the form of cylindrical rings, and are respectively secured to the inside wall of the vacuum vessel by a mount.
In this known structure, at least one mount must be provided for each electrode, the mount being in mechanical connection with the inside wall of the vacuum vessel. Such an electrode system is extremely complex to manufacture, because a specific mount is required for each electrode. Moreover, the assembly time is significant, because the electrodes must be individually adjusted.